1. Field of the Invention
The present invention relates to a dishwasher and a controlling method thereof.
2. Description of the Related Art
A dishwasher is a home appliance that sprays high-pressure wash liquid within a tub to wash and remove food residue and other impurities left on surfaces of dishes. A filter filters the food residue from the wash liquid to recycle the latter, and detergent is dissolved into the wash liquid to facilitate the removal of food residue.
In order to improve the above dishwashing process, the following dishwasher functions have been developed.
First, by heating wash liquid to aid in dissolving the detergent, overall dishwashing effectiveness can be improved. Also, by heating wash liquid, the wash liquid can more easily remove glutinous rice and other hardened food residue.
Furthermore, by dividing the wash cycle of a dishwasher into a pre-wash cycle and a main wash cycle, the pre-wash cycle soaks hardened food residue, so that it can be more easily removed in the main wash cycle. Another method being employed is removing germs and sterilizing dishes by emitting ultraviolet light onto the surfaces of dishes.
However, despite the above devised methods according to the related art, the problem of increasing dishwashing efficiency remains. Especially in oriental households, where in many cases, the staple food is glutinous rice, the latter is difficult to effectively remove from dishes, exasperating the problem of dishwashing efficiency. Even the use of hot water to soak food residue cannot completely obviate the above problem. Also, because soaking requires a prolonged amount of time, it lengthens the duration of the wash cycle.
The above problems reduce the overall washing efficiency of a dishwasher.